Keep in mind you will be completing the financial aid forms each year. Your income and financial situation may change year to year due to unforeseen circumstances. When you are filling out the forms now it is for an estimate of freshman year costs only, not for the next four years. When you fill the forms the following year you might find you owe a different amount. (likely more) Take into account the distance from home. Air travel is expensive especially if they plan to travel home over the holidays. (peak time) If you have two children in college at the same time the scenario will change as far as aid.
Based on what you described - dual income, three kids in private school, funded 529's realize you are in a better situation than a lot of families so you should feel fortunate that you were able to provide your children with such opportunities. Not every family has that luxury.
Another thing to think about is what your children plans to study in college. Will a bachelor's degree be their terminal degree or will they need to pursue further graduate studies? Would you be contributing to their education if they plan to continue with further studies? Will you still be able to save for your retirement if you do plan to contribute to their further studies. Each child's application experience is going to be different and so will their needs.
I don't know your situation but I myself would not apply ED. I personally would like to compare aid offers if that was possible and pick the school that was a good personal and financial fit. There are many good schools out there and I personally feel it is better not be hung up on one school. For those families where the cost is not an issue and they really like one school ED is very suitable option for them.
What another family is doing or if someone chooses to be a SAHM is none of your concern. That is their family decision.
Analyze the risks of applying ED and determine if you are willing to take those risks based on how much you would be able to pay. Keep in mind the tuition will increase every year. You don't want to be in a situation where the child attends the first year and is forced to transfer because you can no longer afford to pay tuition at the school.
Either you have already set aside funds for college to pay for the four years or you are dependent on future income to pay the attendance costs. One thing to consider is if you have younger children who will be attending college in the future. You don't want to use all your savings for one child and not have anything left for the next one. Also there is likely a difference in what you can pay and what you are willing to pay. Determine what that amount is and if you feel this college would be in that range and it is your child's first choice without a doubt then apply. If later you decide to decline the offer realize that you will be applying to other schools Regular Decision where admission maybe more difficult.
If you are out of state or instate for UVA and applied early action there is a good chance he would get deferred because of his grades. They would probably want to see mid year grades before making a decision. I would consider this a reach school not a match given his current transcript.
@annamom That's also true but I wouldn't take for granted getting deferred by applying EA. If the gpa is low the applicant may get outright rejected.
Early action is good for a student that already has strong stats to apply because the pool is smaller for EA than RD.